1. Field of the Invention
The present invention relates to a load balance adjusting method and an equipment of a lifting jack, and a jack-up equipment, and to the load balance adjusting method and the equipment of the lifting jack, and the jack-up equipment suitable for raising/lowering a boiler module without disrupting the load balance when the boiler module of a large scale electric-power plant is raised/lowered by using plural lifting jacks using suspending rods.
2. Description of Related Art
In a thermal power station having large suspending type boilers, a main beam for supporting the boilers is provided at a top end portion of a steel frame to be a suspending fabric, and boiler components are supported in a state suspended by this main beam. For this construction, a lifting construction method is generally adopted. In this construction method, plural lifting jacks placed on a supporting beam such as a temporary beam or the main beam are used, attendant parts are assembled while a module being the boiler component is lifted from the ground by using the lifting jacks, and finally, it is suspended and supported by the main beam at dozens of meters upward from the ground by using a sling rod and so on. Such works are performed repeatedly by each module from the module assembled at an upper portion of the boiler to the module assembled at a lower portion of the boiler sequentially to thereby build a whole boiler facility.
As shown in FIG. 5, steel columns 12 are placed around a boiler module 10 being a massive structure, and a temporary beam 14 is provided at an upper portion of these steel columns 12. Center hole type lifting jacks 16 are arranged on this temporary beam 14, and suspending rods 18 attaching the boiler module 10 at lower ends thereof are supported.
As shown in FIG. 6, the above-stated suspending rod 18 has a configuration in which short single rods 18S are coupled by screwing each other in an axial direction to be elongated. A structure of the single rod 18S is the one that a head portion 22 having a slightly large-diameter is formed at an upper end portion of a rod portion 20, a female screw portion 24 is formed at a top end surface of the head portion, and a male screw portion 26 is formed at a lower end of the rod portion 20. A piece of long suspending rod 18 is formed by continuously connecting respective single rods 18S in a screwed coupling with each other, and a jacking-up is enabled by using the head portion 22 of the single rod 18S.
The center hole type lifting jack 16 raising/lowering such suspending rod 18 is suspending and raising/lowering the boiler module 10 with hanging and supporting in a state penetrating the above-stated suspending rod 18 into a center hole 28 opened in longitudinal directions. This structure is shown in FIG. 7.
Namely, in the center hole type lifting jack 16, a cylindrical ram 32 driven by a hydraulic pressure is disposed inside of a cylinder 30, an upper chuck 34 and a lower chuck 36 sliding in an orthogonal direction with an axis of the suspending rod 18 are provided at an upper portion of the ram 32 and at a lower portion of the cylinder 30, and the suspending rod 18 is supported and pushed upward by these chucks 34, 36 to thereby jack up the boiler module 10.
As shown in FIG. 8, a procedure of the jacking-up is as follows: at first, the suspending rod 18 suspending the boiler module 10 is supported by the upper chuck 34 (supporting rod No. 2); a load of the boiler module 10 is received by the upper chuck 34 (first stage). Next, the lower chuck 36 is released. The ram 32 is actuated in this state, the suspending rod 18 is pushed up for the length of the single rod 18S, and the boiler module 10 is jacked up via the suspending rod 18 (second stage). Next, the lower chuck 36 is closed at a position the suspending rod 18 raises for one rod (third stage). The ram 32 is lowered to transfer a supporting portion to a supporting rod No. 5 by the lower chuck 36, and the load of the lifting (suspending load) is received via the corresponding supporting rod No. 5. When the lower chuck 36 supports the suspending rod 18, the upper chuck 34 is released to further lower the ram 32 (fourth stage). When the suspending rod 18 comes to below a neck portion of a supporting rod No. 3 positioning one lower of the supporting rod No. 2 supported by the upper chuck 34 until that time, the upper chuck 34 is closed again to support the suspending rod 18 by the upper chuck 34, then the lower chuck 36 is released, and the above-stated operation is repeated. As stated above, when a coupling position of the suspending rods 18 with each other comes up to an upper portion of the center hole type lifting jack 16, the single rod 18S at the upper portion is detached. These first to fourth stages are repeated sequentially, and the boiler module 10 is jacked up while retrieving the single rods 18S from an upper end portion.
By the way, when the above-stated boiler module 10 is raised/lowered by the center hole type lifting jack 16, it is performed by using plural center hole type lifting jacks 16. It depends on a module weight, but for example, a module of 3000 tons to 4000 tons is lifted by using twenty or more center hole type lifting jacks 16 whose self-loading is 200 tons. Consequently, it is necessary to make a raising/lowering drive while averaging the loads of the twenty center hole type lifting jacks 16. When one boiler module 10 is jacked up by plural number of lifting jacks, for example, ten jacks for one line are provided two lines to perform a jack-up. Generally, the loads shared by respective jack lines are different with each other, but the loads shared by the jacks within the same line are set to be averaged, and it is necessary that the loads are not fluctuated from an initial shared load. If a load balance is fluctuated, a problem may occur such that an excessive load is added to a single jack and so on. Generally, a connection length of the boiler module 10 and the suspending rod 18 is adjusted so that the shared loads of the respective center hole type lifting jacks 16 within the same line are to be equal in an initial state when the boiler module 10 is lifted up from the ground first.
However, when the boiler module 10 is lifted while detaching the single rods sequentially from the upper end of the suspending rod 18 from an initial setting state, a length of the whole suspending rod becomes short. As a result, there is a problem that the shared loads are fluctuated from an initial value which is set so that the shared loads of the respective center hole type lifting jacks 16 are averaged, caused by a connection cumulative error of the suspending rod. Conventionally, it is impossible to adjust such fluctuation of the shared load in the middle of the lifting.
Besides, the loads imposed by the respective center hole type lifting jacks 16 are asked from a pressure of an operating oil supplied inside of the jacks. However, there is a problem that a detection value may be dispersed even if a supplied pressure of the operating oil during the actuation of the jack-up is detected. Namely, there is a problem that an accurate detection can not be performed because a dynamic pressure is detected.